Electrolytic process and apparatus



Aug. 20,l 1935. J. E. JEWETT 2,012,046

ELECTROLYTIC PROCESS AND- APPARATUS Filed Jan. s1, 1930 2 sheets-sheet 1 )f lllllllll i i .t A I L l l.. ETI.

Aug. 2o, 1935. J l.; JEWETT 2,012,046

ELECTROLYTIC PROCESS AND APPARATUS Filed Jn. 5l, 1930 2 Sheets-Sheet 2 'I vez? Zar Josep 0 e?? Patented ug. 20, 1935 PATE 2;o12,o4 s ELEcTnoLYTIc mocEss -AND APPARATUS `Joseph E. Jewett, Buffalo, N. Y., assignor to National Aniline and Chemical Company, Inc., New York, N. Y., a corporation of NewYork Application January 31, 1930, Serial No. 424,910

17 Claims.

The present invention relates to improvements in processes and apparatus for carrying out electrolytic reactions, and is particularly adapted for carrying out the electrolytic reduction of nitro,

azoxy, or azo bodies.

In the manufacture of hydrazobenzenes by the electrolytic reduction of the corresponding nitro, azoxy or azo bodies, lthe reduction .products are precipitated as solids which stick to the diaphragms and walls of the electrolyzer and decrease the eiciency vof the apparatus. Frequently, the solids are deposited as a hard mass which is diicult to remove.

One object of the present invention is the provision of a process for conducting electrolytic reactions wherein the electrlytic solution is passed between the diaphragm and the electrode to keep the surfaces free from incrustation. Another object is the provision of an ele'ctrolyzer wherein the liquor in the space between the electrodes and diaphragm is kept in circulation to prevent the deposition of solids on the walls of the apparatus. Another object is the design of an electrolytie cell which is compact and is convenient to assemble and disassemble, and which is inexpensive to manufacture, occupies little oor space, has a high output per unit of capacity and a low power cost in comparison with cells of the same type. These and other objects are accomplished in the 'practice of the present invention.

An illustrative embodiment of a manner in which the process may be carried out in practice and of anapparatus in which the process may be practiced is shown in the accompanying drawings wherein Figure 1 is a side view partly in section of an assembled apparatus; Figure 2 is a plan view; Figure 3 is an end view; Figure 4 is a section of a detail taken on line 44--4 of Figure 2; Figure 5 is a section of a detail taken on line 5-5 of Figure 1; Figure 6 is a section on an enlarged scale of a detail taken on line 6-6 of Figure 1; Figure '7 is an enlarged view of the cell fastening means; and Figure 8 is a diagrammaticl view of the circuit through which the anode liquor flows.

Referring to the drawings, the numerals I, I'

indicate a pair of end cheeks or standards which are connected by a pair of longitudinally extending parallel bars 2, 2. The electrolyzer is constructed of a plurality of cells or units in pairs 3, v3 which may be of any number desired, and

tween the cheek Ii and follower 5 by a suitable clamping mechanism indicatedgenerally by the A sheet 1 of insulation material is interposed between the cheek I and rst unit 3, and a similar sheet 8 of insulation material is interposed between the follower 5 and the last unit, to insulate the units from electrical contact with the follower'5`and cheek I. 'I'he units 3, 3 are each equipped at the bottom on each side with lugs- 9, 9', through which pass the insulation sleeves I0, suitably keyed to the lugs. A shaft I I passes through the insulation sleeves I0 and is suitably keyed thereto, and at its outer ends carries the -iianged wheels I2 rotatably held thereon by suitable means and insulated from-electrical contact with the lugs by insulation washers I3. 'I'he wheels I2 operate on the guide rails I4 and I4' to permit ea'sy manipulation of the units in assembling and disassembling the electrolyzer. The electric current enters the apparatus at the terminal I5 and leaves the apparatus at the terminal I5.

Each unit 3, 3 comprises a hollow casing or frame I6 of generally rectangular shape which may be constructed of cast iron or other suitable conducting material. A horizontal web or partition I1 spaced from the diaphragms 4, 4' divides the interior of the frame I6 into an upper compartment I8 and a lower compartment I9. A wall 20 forming an' anode completely closes the side 20 of the upper compartment I8 and is spaced from the diaphragm 4 to form an anode chamber 2| therebetween, which communicates at its bottom 22 through the opening 23, with the lower compartment I9. A second wall 24,

, forming a cathode, blocks the other side 24' of Vvertically extending warped wall or partition 30 diagonally divides the lower compartment I9 into a lowerv anode compartment 3| and a'separate lower cathode compartment 32.

On the sides of the anode 20 and cathode 24 are cast the parallel spacing ribs 33 which lie flush with the flanges 34 which extend around vthe perimeter of the units 3; 3, at both sides 20,', 24. Lugs 35 are cast integral with the anges 34 and are slotted-at v36 to receive the numeral 6, which may be hydraulicallyoperated.

insulation sleeves 31. 'In assembly the runits 3, 3 are clamped together with the diaphragms 4, 4', etc., therebetween, resting against the flanges 34 and ribs 33, and are held in clamped position between the end cheek and follower 5. 'I'he bolts 38 pass through the insulation washers 39' and sleeves 31 in the slotted lugs 35. Nuts 40, insulated from electrical contact with the lugs 35 by the insulation washers 39, are threaded onto the ends of the bolts 38 and hold the diaphragms 4, 4', etc., and units 3, 3', etc., in assembled position when pressure on the follower is released to disassemble the electrolyzer or for any other reason.

The lower anode liquor chamber 3| communicates with fthe anode compartment 2| through theopening 23, and receives its supply of anode liquor through supply passage 4|. The lower cathode liquor chamber 32v communicates with the cathode compartment 26 through the opening 42 at its bottom 21, and re'ceives'its supply of cathpump casting indicated generally by the numeral 4'9 havin/g a rotor chamber 50 therein. The pump casting 49 has a pump discharge passage 5| therein, leading from the periphery of the rotor, which is flanged at its outer end, as indicated at 52, and a curved pump supply passage 53 leading to the center of the rotor, which is also flanged at its outer end as indicated at 54. At one end of the pump'v casting 49 the spacer 55 is suitably secured,

andat the other end of the spacer the motor 56 is secured. The entire assembly comprising the pump casting 49, the spacer 55 and motor 56 is secured to the respective units by the bolts 51 which pass through alined bores 58 in the flanges 52 and 41, respectively, and flanges 54 and 45, respectively, thus forming a continuous passageway from. cathode reservoir 25, passage 44, passage 53, rotor chamber 50, passage 5| and passage 46.

In assembly, an upper anode compartment 2| is formed between the diaphragm 4 and the wall 20, which functions as an anode, communicating at its bottom with the lower anode chamber 3| through the opening 23. The upper cathode compartment 26 formed between .the wall 24, which functions as a cathode, and diaphragm 4', communicates at its bottom 21 with the lower cathode chamber I9 through the opening 42. The wall 24 does notextend completely to the top of the casing, but terminates at 28, some distance from the top, leaving an open space 29 which communicates with the cathode reservoir 25. The wall 20 extends fully to the top of the unit, but is oset at its top at 59 to provide a compartment 60 communicating with the upper anode compartment 2|, but is closed off from the cathode reservoir 25.

The operation of the apparatus will now be described in connection with the reduction of nitrobenzene to hydrazobenzene, but it is to be understood that the invention is not limited thereto. In operation, anode liquor is supplied to the lower anode compartments 3| as a continuous stream through the supply passages 4| from lead-in supply pipes 6I. Lead-in supply pipes 6| have funnels 62 at their upper ends, each receiving a passages 26.

dripping stream from main anode liquor supply4 pipe 63 which runs parallel to the assembled electrolyzer. As shown, the supply passages 4| and 4|' are on alternate sides of alternate units. Supply passages 4| and 4|', communicating with lead-in supply mains 6| land 6| on opposite sides of the electrolyzer, correspond in the respective units 3 and 3. A main anode liquor supply pipe lines 63 and 63' to be reused. The anode liquor may be reused till exhausted.

Cathode liquor is introduced into each unit .through the inlets 43 communicating with the lower cathode compartments 32 and i-s shut ,off when the liquor fills the upper cathode compartment 26 and cathode reservoir 25 to the upper edge 28 of the cathode 24. The cathode liquor is supplied to the units from main supply pipes 68 through rubber4 connections 69 Ito the inlets 43. 'I'he pumps 48 are set in operation and circulate the cathode liquor through pump discharge 5|, passage 46, lower cathode chamber |9, through opening 42, into upper cathode chamber 26 and overflows at the top 28 of the cathode 24 into cathodereservoir 25, whence it is withdrawn through passage 44 and pump supply passage 53 to the pump to be recirculated. The liquor in the cathode compartments is kept at about 95 to 98 C. by suitable heating means (not shown). The electric current enters the apparatus at the terminal 5 joined to an anode and passing through the anode liquor, diaphragm and cathode liquor successively, leaves the apparatus at the terminal I5 joined to a cathode. The nitrobenzene in the cathode compartments is reduced to hydrazobenzene, which is prevented from depositing on the walls of the diaphragms and cathodes by the circulation of liquor through the When the reduction is complete, the cathode liquor is drained from the cathode compartments through the pipes 43 which serve as both a drain and supply pipe and the apparatus is ready to receive another charge of cathode liquor.

Each unit 3, 3' is provided with a vented coil 1| connected to the cathode chamber at its top through the pipe 12. Material which volatilizes in the cathode chamber passes into the condenser coil 1| where it is condensed and returned to the cathode chamber. A pipe 13 connected to each anode chamber, is connected by the insulation coupling 14 to a common vent line 15. Vapor from the anode liquor passes through the pipe 13, and coupling 14 into the vent line 15, and is conducted to the condenser 16 where it is condensed. and discharged into a mixing tank by the pipe 11. From the mixing tank the liquor flows into the mains 63 and 63 and is fed back intothe cells.

When it is required to take down the apparatus for cleaning or for any other purpose, the nuts 40 are turned off the bolts 38 at the desired separation point, and the follower is retracted, drawing with it along the rails I4, I4' units on that side of the separation point. After cleaning,

, anode parallel to the one diaphragm and spacedl therefrom to provide an anode chamber, a cath# zene, thel process which `,comprises flowing the cathode liquor in a stream through the space formed between the cathode and diaphragm to keep vthe surfaces of the cathode and diaphrag free from incrustations.

2. In the electrolytic reduction of nitro compounds, the process which comprises flowing the cathode liquor in a stream through the space formed between: the diaphragm and cathode plate, cascading the cathode liquor over the cathode plate into a reservoir, and recirculating the cathode liquor.

3. An electrolyzer comprising an open-sided frame having its sides closed by diaphragms, ani

ode parallel to the other diaphragm and spaced therefrom to provide a cathode chamber, a cathode reservoir, means for supplying anode liquor to the anode chamber in a continuous stream,

means for supplying cathode liquor to the cath- 'r ode chamber and reservoir, means for flowing cathode liquor through the cathode chamber and I l compartment therebetween which communicates at its bottom with the lower compartment, auxfor circulatingA the cathode liquor between the cathode chamber and cathode reservoir.

4. -An electrolyzer comprising a plurality of units having diaphragms interposm therebetween, a press for holding said units, in position, insulation members separating the end units from electrical contact with the press, said units each comprisingan anode platev slightly spaced from and ,parallel to a diaphragm to form a separate anode chamber therebetween, a cathode plate slightly spaced'r from and parallel .to the preceding diaphragm to form a separate cathode chamber therebetween, meansy for supplying anode liquor to each anode chamber in a continuous stream, means for carrying away the overflow from each anode chamber, .means for supplying cathode liquor to each cathode chamber, and independent means for Veach unit for circulating cathode liquor through the cathode chamber to keep the walls thereof free from incrustation.

5. An electrolyzer of the character described comprising a plurality of units clamped together and separated by diaphragms, a press for holding said units in clamped position, insulation members separating the end units from electrical contact with the press, each unit comprising an open-sided frame flanged at its sides to provider bearing surfaces for the diaphragms, and means independent of said press for holding the units and diaphragms (in clamped position when the pressure of the press is released.

6. An electrolyzer comprising a plurality of plate and diaphragm, .and reinforcing ribs interposed between said anode plate and diaphragm against which said diaphragm bears on its opposite side, forming an anode chamber between the anode plate and diaphragm.

7. An electrolyzer of the character described comprising a plurality of units clamped side by side and separated by diaphragms, each unit comprising an open-sided frame flanged at its sides to provide a bearing surface for the diaphragms, a cathode plate spaced from one diaphragm to form a cathode compartmenttherebetween, an anode plate parallel to and spaced from the other diaphragm to form an anode compartment therebetween, a pump clamped to the unit, a pump discharge passage communicating with the lower part of the cathode compartment, and a pump supply passage communicating with the upper 4part of the cathode compartment.

8. An electrolyzer comprising a plurality of units clamped s ideby' side and separated by diaphragms, each interior unit comprising an opensided frame flanged at its sides to provide bearing faces for the diaphragms, a partition spaced from the diaphragms, dividing the interior of the frame into an upper and a lower compartment, a plate forming an anode completely closing one side of the upper compartment and spaced from the diaphragm to form an anode iliary bearing means interposed between the diaphragm and anode plate to provide auxiliary support for the diaphragm, a cathode plate on the opposite side of said unit, said cathode plate `being spaced from and disposed` parallel to the adjacent diaphragm to form a cathode chamberl 1 which communicates at the bottom withI said lower compartment auxiliary bearing means interposed between the latter diaphragm and cathode plates to provide auxiliary supportfor the latter diaphragm, and a partition dividing said lower compartment into separate lower anode and lower cathode compartments.

9. An electrolyzer of the character described comprising a plurality of units clamped side by side, and separated by diaphragms, each unit comprising an open-sided frame having a partitween which communicates at its bottom with the lower compartment, a second wall forming a cathode blocking the other side of the upper compartment, spaced from the anode to form a cathode reservoir therebetween, and spaced from the other diaphragm to form a cathode chamber therebetween, the cathode chamber communlcating at its bottom with the lower compartment and communicating at the vtop with the cathode reservoir, a passage communicating with the cathode reservoir, a partition dividing the lower compartment into a lower anode compartment and a separate lower cathode compartment, a passage communicating with the lower cathode compartment, means for supplying anode liquor to the anode compartment. means for supplying cathode liquor to the cathode compartment, and means for circulating the cathode liquor through the lower cathode compartment, cathode chamber and cathode reservoir.

, comprising a plurality of units clamped together g vand separated by diaphragms; a press for holding ode parallel tothe other diaphragm and spaced therefrom to provide a cathode chamber, a cathode reservoir, and .means for `circulating cathode liquor through the cathode chamber between the cathode and the diaphragm and into the cathode reservoir.

12. An electrolyzer comprising an open-sided frame having its sides closed by diaphragms, an anode parallel to the one diaphragm and spaced therefrom to provide an anode chamber, a. cathode parallel to the other diaphragm and spaced therefrom to provide a cathode chamber, a web dividing the space between the anode and the cathode into an upper and a lower cathode compartment, and means for circulating cathode liquor from the lower cathode compartment through the cathode chamber and into the upper cathode compartment.

13. An electrolyzer of the character described,

the said units in clamped position, and mean's independent of said press and carried by said units for holding the units and diaphragms in clamped position when the pressure of the press is released.

14. An electrolyzer of the character described comprising a plurality of .units clamped together and separated by diaphragms, a press for holding said units in clamped position, insulation members separating the end units from electrical contact with the press, each unit comprising an opensided frame having diaphragms positioned at and closing its sides, and means independent of saidand diaphragms in clamped'position when the pressure of the press is released.

15. An electrolyzer of the. character described comprising a plurality of units clamped side by side and separated by diaphragms, each unit comprising an open-sided frame flanged at its sides to provide a bearing surface for the diaphragms', a cathode plate spaced from one diaphragm to form a cathode compartment therebetween, an anode plate parallel to and spaced from the other diaphragm to form an anode compartment therebetween, a web dividing the space .between the cathode plate and the anode plate into an upper and a lower cathode compartment, and means for passing cathode liquor from the lower compartment through the cathode chamber and into the upper cathode compartment.

16. An electrolyzer `comprising a plurality of units clamped side by side and separated by diaphragms, each interior unit comprising an opensided frame, a partition spaced from the diaphragms dividing the interior of the frame into an upper and a lower compartment, a lpartition dividing said lower compartment into separate lower anode and lower cathode compartments, a plate forming an anode completely closing one side of the upper compartment'and spaced from the diaphragm to form an anode compartment therebetween which communicates at its bottom with the lower anode compartment and a cathode plate on the opposite side of said unit, said cathode plate being spaced from the adjacent dia-i A.ode liquor, the improvement which comprises flowing the cathode liquor in a stream through the space formed between the cathode and the diaphragm to keep the surfaces of the cathode and diaphragm free from incrustations of said precipitated solid.

, `JOSEPH E. JEWETT. 

